1. Field of the Invention
The present invention relates to a recording apparatus for transmitting or recording a video signal and to a reproducing apparatus for reproducing the video signal.
2. Description of the Prior Art
It is known that the conventional television signals are transmitted or recorded on a frame by frame basis. Each frame comprises two fields in which a horizontal scanning line of one field falls between two adjacent horizontal lines of the other field in the frame. This is called as interlaced scanning.
Accordingly, the video signal is transmitted or recorded as interlaced signals in a video signal transmitting or recording apparatus. For reproduction of the video signal, the two fields are interlaced to one frame. The frame by frame basis recording, transmission, or reproduction is applicable to not only a motion image but also a still or slow-motion image.
However, there are some drawbacks with such conventional video signal recording or reproducing apparatus:
(1) In common home video game machines, two corresponding horizontal lines of their respective fields of a frame are allocated to the same location on a screen for preventing flicker caused by interlacing of the two fields. They are thus called non-interlaced fields. If such a non-interlaced video signal transmitted or recorded is interlaced in reproduction, it will produce flicker. P (2) For a still image shot by a camera, each field of its data is temporarily stored in a memory and then transmitted or recorded for a plurality of field periods. Such still image data will also produce flicker when interlaced and reproduced, similar to the non-interlaced signal of the paragraph (1).
(3) While a recorded TV signal is reproduced in a slow-motion or still mode, a single field of its data is continuously pulled for a plurality of field periods. Such slow-motion or still image data after transmitted or recorded will produce flicker when interlaced and reproduced, as well as the still image data of the paragraph (2).
(4) If still images and motion images are recorded in a combination, they will hardly be discriminated from each other during the reproduction. Also, it will be difficult to determine whether a still or slow-motion image is reproduced on a frame by frame basis or a field by field basis.
(5) When an error occurs during the reproduction of a still image, it is generally eliminated by error concealment. However, since two consecutive frames are not always correlated, a technique of inter-frame concealment can unsuccessfully be used. If the inter-frame concealment is enforced, the quality of a reproduced image may critically be impaired.
(6) When a still image is recorded in multiple frames, it will be hard to identify the starting frame of a succeeding still image and the searching of still images by frames will almost be infeasible.
(7) Any image data which has been reproduced in a slow-motion or still mode and transmitted or recorded will hardly be identified whether it is a common motion image or a slow-motion or still image.